Hello. Maybe you know already (because the problem seems to be lack of maintainer). But there is a python-uniconvertor 2.0 that no longer depends on python-imaging but on python-pil (python2, I believe)
https://sk1project.net/modules.php?name=Products&product=uniconvertor&op=download They offer source and some .debs for a couple architechtures and Debian 9, but I haven't tried them or audited the licenses or anything. I suppose it would still require packaging. Unfortunately I don't know enough about debian policies or about python. I might try to learn, but I think Debian is frozen now ?
